For those of us who like to tinker, the DIY unit is a fun project and is certainly a lot less expensive than the plug-n-play PID controller. I installed mine in the SG. The plug-n-play does have more features, none of which I would ever use. I think I paid around $70 for all the parts to build mine.

Does one setup work better than another? Or is it just a case of the same performance, but cheaper to DIY?

Either setup will maintain the chamber temp to within a couple of degrees, if that's all you want it for. The plug-n-play is obviously easier to install (just plug it in) but not as much fun if you like to build and modify things.